A thin film is caused to adhere to the surface of an article to provide the article with a favorable design or to add some function to the article. For example, a colorful film imitating stained glass or a nontransparent film to protect privacy may be caused to adhere to a transparent window of a building, or a UV ray shielding film is caused to adhere to vehicle windows to protect the skin of passengers and drivers. Because applying film to an article can protect the surface from air (oxygen), applying films instead of providing a coating is favorably accepted.
It is well known in the art that neatly applying a thin film onto the surface of an article is difficult. One reason is a difficulty in precisely positioning the film on the article. Another reason is invasion of air between the article and the film. The air may remain as bubbles after applying the film, resulting in an unfavorable appearance. If the application job is not quickly completed, a line mark (a shock line) may be formed in the area in which the application job is suspended, and this would result in impairing the external appearance. In the case where a film has an adhesive layer on the side contacting an article, the film must be so positioned that the adhesive does not come into contact with an application surface to maintain the adherence of the film to the article for a long period of time. This requirement increases the difficulty of the job for neatly and accurately applying the film to an article.
For instance, some automobile assembly lines have a step of applying a thin film (e.g., a narrow width paint replacement film) onto the surface of the automobile. More specifically, for example, in a door sash frame 80 of a vehicle shown in FIG. 9, a black adhesive tape (i.e., an adhesive-backed paint replacement film) is applied to improve the design of the vehicle by making the window outline of the door black. The black adhesive tape, for example, comprises a film layer (made of vinyl chloride, for example) as a substrate and an adhesive layer (an acrylic-type pressure sensitive adhesive, for example) provided on the back side of the film layer. In the past, the door sash frame 80 was colored with a conventional coating of paint. However, a coating operation increases the environmental load due to splashing of solvent and liquid waste therefrom and requires a considerable number of process steps and a significant operation cost. For these reasons, an adhesive-backed tape having a colored film layer (i.e., an adhesive-backed paint replacement film) has become more popular in recent years.
A seam impairs the appearance when a black adhesive tape is applied along the door sash frame of a vehicle. Therefore, in the case where the door sash has a contour figuring a curve in a conspicuous position, a piece of long tape is preferably applied along the area including the curve. The curve herein refers to a curve 91 of a door sash frame 80 of a vehicle shown in FIG. 9, for example.
However, when an adhesive tape is applied along the door sash frame of a vehicle, the application operation may not follow a curve in the door sash frame. The adhesive tape may deviate from the application surface, requiring that the application operation be carried out again from the beginning. There is another problem that a long period of time is required for an adhesive tape application operation because the adhesive tape cannot be properly positioned on curved lines in a short time. Because all these problems decrease productivity and increase costs, improvement of technologies has been desired.
Tools useful for applying an adhesive tape have been proposed to solve these problems.
For example, Japanese Patent Application Laid-open No. 123127/2001 proposes an adhesive tape application tool shown in FIG. 3, which is capable of consistently and precisely applying an adhesive tape at high speed. The adhesive tape application tool 101 applies an adhesive tape with a release paper to a door sash frame 80 while removing the release paper by causing the tool to move along a door sash frame 80 of a vehicle. The adhesive tape can be applied without bubbles included therein because the tool is provided with an elastic roller 105 which presses the adhesive tape against the tape-applying surface of the door sash frame 80. In addition, a guide roller 106 with a concave groove 116 is formed on the back of the tape applying surface of the door sash frame 80. The guide roller 106 engages a projected line portion 83 (convex) extending longitudinally along the door sash frame 80, whereby high precision positioning can be ensured. The tool can accurately apply an adhesive tape in this manner.
However, many vehicle designers in recent years prefer a curve with a small radius for a door sash configuration or a curved configuration with a corner rather than a smooth curve. This inevitably requires the projected line portion 83 (convex) extending longitudinally along the door sash frame 80 to also be formed with a steep curve or a corner. In such an instance, a guide roller 106 with a concave groove 116 can engage the projected line portion 83 (convex) at the curve of the door sash frame 80 due to an inside-outside ring difference. As a result, if the adhesive tape is applied at a stretch, deviation of the adhesive tape may occur in the curve; or, if the tool is caused to travel slowly in the curve to avoid derailing the guide roller 106 with a concave groove 116 from the projected line portion 83 (convex line), the adhesive tape may include bubbles which result in a shock line.